1. Field of the Invention
The present invention relates to a method and apparatus for ensuring post-assembly fitness of printed circuit boards for use in a safety-related system and ensuring defective printed circuit board assemblies are not utilized in finished products. More particularly, the present invention relates to a method and apparatus for preventing untested or improperly tested printed circuit boards from being used in a fire pump control system by interrogating each printed circuit board to ensure post-assembly fitness.
2. Description of Related Art
Printed circuit boards (PCBs) are typically tested during various points during its manufacturing process. After a particular test or test sequence has been completed, the PCBs that have failed a test may be separated from the PCBs that have passed all tests. The functional PCBs are usually ink-stamped or similarly marked to indicate that the PCBs have passed all tests prior to shipping to a customer. Typically, no records are maintained concerning the tests performed on each PCB or the results thereof.
An unfortunate outcome of the conventional test sequence is a lack of quality control. For instance, a faulty PCB may inadvertently be sorted with the functional PCBs, and therefore be erroneously marked as having passed all tests performed on it. The faulty PCB is then shipped to an unknowing consumer who will install the faulty PCB into a fire pump control system assuming that the faulty PCB is fully functional due to the erroneous mark of approval.
The faulty PCB in the fire pump control system may not be exposed until the fire pump control system as a whole ceases to operate correctly or fails a routine safety inspection.
Since no test record for the faulty PCB is maintained by the manufacturer, this typically results in a very time-intensive process requiring that each PCB component be removed from the faulty fire pump control system and similarly placed inside a working fire pump controller system in order to be properly tested. A hardware diagnostic test is usually run to test whether each PCB component from the faulty fire pump system is working properly. This lengthy process continues until the faulty PCB component is isolated and replaced.
The conventional alternative to the time-intensive process described above, is to simply replace the entire faulty fire pump control system. This, however, is a costly option since many fully functional PCB components in the faulty fire pump control system may be discarded unnecessarily.
Accordingly, there is a need for an improved method and apparatus that decreases the cost and complexity of replacing a faulty PCB in a fire pump control system by preventing untested or improperly tested printed circuit boards from being used in a fire pump control system.
Such a method and apparatus preferably would store the test results of each PCB component on its non-volatile memory to provide a more extensive and long-term record than the contemporary method of merely noting test results by ink-stamping or marking the PCB component.
Additionally, such a method and apparatus preferably would maintain a test history of each PCB on its non-volatile memory so that the test history of the PCB can be instantaneously probed by a fire pump control system operator upon installation, thus eliminating the cost and complexity of having to retest individual components of a fire pump control.
Further, such a method and apparatus preferably would automatically interrogate and verify the fitness of each PCB component in a fire pump control system, thus improving the efficiency and cost of manually testing each of the PCB components.